Torsion bar assembly and method, particularly for rail vehicle anti-roll bar

Abstract

A heavy duty torsion bar assembly, particularly an anti-roll bar assembly for a rail vehicle, includes a lever which is mounted on the bar by an oil injection taper fit, the cooperating surfaces having a drainage groove and being formed to a tolerance of IT7 or better, wherein the final assembled position is determined by a pre-defined axial displacement of the lever from an initial position defined by manual engagement of the two parts.

The invention claimed is: 
     
       1. A dismantlable torsion bar assembly comprising:
 a torsion bar; 
 at least one lever; 
 the torsion bar having a tapered external surface of rotation formed at an end portion thereof; 
 the lever having a socket defining a tapered internal surface of rotation; 
 the socket being adapted to receive the end portion of the bar in an assembled position in which the respective surfaces of rotation cooperate in frictional tapered fit relation to define an interface therebetween; 
 the end portion of the bar having a threaded bore opening at an axial end surface thereof; 
 a pressure fluid injection port adapted to deliver a supply of pressure fluid to the interface in the assembled position; and 
 at least one of the respective surfaces of rotation having a pressure fluid drainage groove communicating with the injection port in the assembled position. 
 
     
     
       2. A dismantlable torsion bar assembly according to  claim 1 , wherein the drainage groove extends for at least 65% of an axial length of the interface in the assembled position and is arranged as a plurality of spaced-apart portions which are distributed over the interface. 
     
     
       3. A dismantlable torsion bar assembly according to  claim 1 , wherein the threaded bore extends for at least an axial length of the interface. 
     
     
       4. A dismantlable torsion bar assembly according to  claim 1 , wherein the respective surfaces of rotation have a taper between 1:30 and 1:80, and the respective surfaces of rotation have a diametrical tolerance of not less than 0.019 mm and not more than 0.030 mm, and a tolerance of at least +/−2.5 mm is provided in the assembled position of the lever on a longitudinal axis of the bar. 
     
     
       5. A dismantlable torsion bar assembly according to  claim 1 , wherein the assembly is arranged as an anti-roll bar assembly in a rail vehicle. 
     
     
       6. A method of assembling a torsion bar assembly, comprising:
 a) providing a torsion bar and at least one lever; 
 b) forming a tapered external surface of rotation at an end portion of the bar; 
 c) providing the lever with a socket defining a tapered internal surface of rotation; 
 d) forming a threaded bore opening at an axial end surface of the end portion of the bar; 
 e) providing a pressure fluid injection port communicating with one of the respective surfaces of rotation; 
 f) providing at least one of the respective surfaces of rotation with a pressure fluid drainage groove, wherein the groove communicates with the injection port in an assembled position of the assembly; 
 g) driving the lever onto the bar such that the end portion of the bar engages in the socket in frictional tapered fit relation to define an initial position of the lever with respect to the bar; 
 h) engaging a tension element in the bore and arranging a jack between the tension element and the lever; 
 i) extending the jack so as to press the lever onto the bar through a first axial distance of travel; 
 j) forcing pressure fluid via the injection port between the respective surfaces of rotation; 
 k) extending the jack so as to press the lever onto the bar through a second axial distance of travel to an assembled position, wherein the assembled position is a predefined axial distance from the initial position; 
 l) permitting the pressure fluid to escape from between the respective surfaces of rotation via the drainage groove and the injection port; and 
 m) removing the jack. 
 
     
     
       7. A method according to  claim 6 , further comprising arranging the torsion bar assembly as an anti-roll bar assembly in a rail vehicle, and inserting the torsion bar through apertures in a bogie of the rail vehicle before the lever is driven onto the bar.